Mold with optimized heat transfer properties

ABSTRACT

A mold ( 1 ) for the production of confectionery products, comprising a top surface ( 2 ) having cavities ( 2   a ) and an opposite bottom surface ( 3 ), comprising at least one protruding element ( 5 ) at the bottom surface ( 3 ) of the mold ( 1 ) for increasing the heat transfer rate between the mold ( 1 ) and a fluid flowing along the bottom surface ( 3 ).

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a U.S. national phase application of InternationalApplication No. PCT/EP2013/060607, filed May 23, 2013, which claimsbenefit from Great Britain Application 1209662.4, filed May 30, 2012,which are hereby incorporated herein by reference in their entirety.

TECHNICAL FIELD

The present invention relates to a mold for the production ofconfectionery products such as chocolate.

BACKGROUND OF THE INVENTION

Molds for confectionery products are one of the most important parts ofthe confectionery production process. Molds determine the design of theproduct, including its final visual quality, as they are the carrier ofthe confectionery product from the first deposit of a liquidconfectionery mass until the final confectionery product reaches thepackaging area. During this process the mold/product system is typicallycooled down or heated up several times by passing it through aprocessing unit which is divided into zones having differenttemperatures, the different temperatures being attained using a seriesof cooling/heating units.

The heat transfer rate between the mold/product system and thecooling/heating air is of fundamental importance to the energyconsumption of the processing unit and the final quality of theconfectionery product.

Conventional molds are generally designed as having a top surface whichcontains specific cavities for the liquid confectionery mass, sideswhich comprise the outer rim and a bottom surface which has variousnumbers of lengthwise and crosswise bars for achieving sufficientrigidity and stability (less bending).

Conventional molds mostly consist of poly-carbonate (e.g. Makrolon,Lexan or Tarflon). Makrolon represents generally the preferred material.Said polycarbonates are food grade, rigid and enable a surface roughnesssmall enough to achieve a glossy chocolate surface.

However, such mold designs are not optimal regarding the fluid dynamicproperties, since dead zones and uncontrolled stationary vortices aregenerated which inhibit heat transfer (see FIG. 1). In general,fluid-dynamic and energetic aspects of the mold as carrier of theconfectionery product are not considered on an industrial scale.Accordingly, the cooling and heating cabinets and their processcapabilities are adapted regardless of the high level of energyconsumption.

A further disadvantage of conventional molds for the production ofconfectionery products is that it is difficult to realize a homogenouscooling/heating of the confectionery mass and thus, a homogenoussolidifying during the production process, since the molds havedifferent wall thicknesses according to the employed shape the cavities.

In general, molds have hitherto been thought of as merely carriers forthe confectionery product mass; they have not been considered as formingpart of the production process.

EP 0 429 969 B1 describes a chocolate mold formed of plastic materialhaving circular openings in the frame which guide the cooling air streamthrough the underside of the chocolate mold. The specific design of saidchocolate mold enables an accelerated, more homogenous cooling/heatingof the chocolate mass during the production process.

The development of a computational model which can predict the coolingbehavior of chocolate in a simple chocolate mold during the commercialmanufacture is described in the article “Modelling temperaturedistributions in cooling chocolate moulds” by P. J. Fryer et al.However, no detailed design of chocolate molds having improvedcooling/heating characteristics is mentioned.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a mold forthe production of confectionery products which has improved heattransfer properties, and a process for the production of confectioneryproducts.

This object is achieved by a mold according to claim 1 . Preferredembodiments of the invention are defined in the dependent claims.

The present invention provides a novel mold with optimized heat transferproperties for the production of confectionery products.

The mold according to the present invention comprises protrudingelements at the bottom surface of the mold for increasing the heattransfer rate between the mold and a fluid flowing along the bottomsurface, and for directing the fluid through the cavities to facilitatethe heat transfer.

The idea of this invention is to improve the heat transfer rate betweenthe mold and the fluid in the heating and cooling tunnels used duringchocolate manufacturing by changing the fluid flow characteristics alongthe molds and if needed by material with higher heat conductivity.

Generally, flow properties and the heat transfer rate are coupled bydynamic and thermal laws of similarity. The idea is to generate a moreintense and turbulent flow along the mold which gives a higher energytransport (Nu=f(Re); wherein Re is the Reynolds number and Nu is theNusselt number). Said more intense and turbulent flow along the mold isachieved via the specific design of the mold according to the presentinvention.

Thus, the specific design of the mold according to the present inventionis driven by fluid-dynamic and thermal aspects. The mold is consideredas part of the process equipment and as having influence on processparameters and conditions, such as energy consumption.

This further leads to new processing conditions and new design criteriafor heating and cooling devices, the optimization of which giving riseto significant advantages in the chocolate production (e.g. energysaving). For example, said reduction of the energy amount needed forcooling and heating processes increases technical efficiency with apositive financial impact and an environmental benefit. Alternatively,the increase in technical efficiency can be used to increase the linespeed and thus the throughput of the production line.

Another advantage of such energy optimized molds in the confectioneryproduction process is the potential for the reduction of the spacerequirement of the processing lines, which further reduces the overallcosts of manufacturing.

Moreover, the specific design of the mold according to the presentinvention allows the confectionery mass to be solidified morehomogenously than using a conventional mold without deterioration inproduct quality (i.e. without fat- and sugar-blooming caused bycondensation) and without the investment, operation and maintenancecosts associated with using conventional molds.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1: Schematic diagram illustrating the generation of dead zones andstationary vortices in the current flow field which inhibit the heattransfer.

FIG. 2: Schematic diagram illustrating a top-side view of an energyoptimized mold (1) according to the present invention.

FIGS. 3-4: Schematic diagrams illustrating various examples ofbottom-side views of an energy optimized mold (1) according to thepresent invention.

FIG. 5: Schematic diagram illustrating vortex generating elements (5)arranged such that they are angularly offset relative to a directionparallel to the fluid flow between the side faces of the mold (1)according to the present invention, guiding the fluid flow andgenerating heat flux.

FIGS. 6-7: Schematic diagrams illustrating various molds (1), whereinthe vortex generating elements (5) are arranged in alternating divergingand converging opposing pairs extending from one side face havingopenings (4) to the other side face having openings (4), the alternatingdivergence and convergence being along a direction parallel to the fluidflow, the diagrams also depicting influence of the arrangement of saidvortex generating elements on the resulting fluid flow.

FIG. 8: Schematic diagram illustrating measurements of online processingparameters and line performances with the help of temperature sensorsand loggers attached to the mold (1) according to the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Preferred embodiments of the mold (1) for the production ofconfectionery products according to the present invention are describedbelow in more detail.

In one embodiment, the mold (1) according to the present invention (seeFIGS. 2 and 3) comprises a top surface (2) having cavities (2 a) and anopposite bottom surface (3), comprising (i) at least one opening (4) inat least one of the side faces of the mold (1) for supplying a fluid tothe bottom surface (3), and (ii) at least one vortex generating element(5) at the bottom surface (3) of the mold (1) for increasing the heattransfer rate between the mold (1) and the fluid. It is to be noted,however, that the provision of openings (4) is not mandatory, and thatflow fluid may flow along the mold via various routes.

The shape of the mold (1) according to the present invention is notparticularly limited, and the mold can have, for instance, arectangular, longitudinally extending top surface (2) or a quadraticextending top surface (2).

The top surface of the mold (1) according to the present embodiment hascavities for the liquid confectionery mass/final confectionery product.The shape of said cavities (2 a) is not particularly limited; thecavities can, for instance, be in the form of a block or tablet (with orwithout breakable portions), a thin sheet or slice, an individualportion or a bar.

The side faces form the rim of the mold (1). In the present embodiment,at least one of the side faces of the mold (1) has at least one opening(4) for supplying a fluid to the bottom surface (3) of the mold (1). Theshape of the opening (4) is not particularly limited and can be, forinstance, circular or rectangular. Preferably, openings (4) are providedin two opposing side faces of the mold (1) so that a flow path can beprovided between the opposing side faces to supply a flow of fluid alongthe bottom surface (3) the mold (1). The provision of more openings (4)in the opposite side faces of the mold (1) can improve thecooling/heating of the mold (1) during the production process.

In addition, the mold (1) can further comprise at least one opening (4)in the top surface (2) of the mold (1) for a more homogenous and morerapid cooling/heating of the mold during the manufacturing.

The bottom surface has at least one protruding element (5) at the bottomsurface (3) of the mold (1) for increasing the heat transfer ratebetween the mold (1) and the fluid by changing the fluid flowcharacteristics. The protruding elements (5) change the fluid flowcharacteristics by producing a more intense and turbulent flow along themold (1) so that the cooling/heating of the mold (1) is accelerated.

Preferably, the at least some protruding elements are shaped as vortexgenerating elements (5) that generate vortices in the fluid whichincrease the heat transfer rate between the warm/cold mold (1) and thefluid by virtue of higher convection. Due to these vortices the fluidwill be mixed more intensely which results in having a more homogeneoustemperature distribution across the mold, i.e. avoidance of stationaryvortices and/or cold/hot spots in, for instance, dead corners. Thevortices, which are generated at the bottom surface of the mold (1),will have, depending on the design of these elements, the abovementioned effects on the bottom surface of the mold (1) as well as onthe top surface of the mold (1).

The shape of the vortex generating elements (5) is not particularlylimited, as long as the elements produce a more intense and/or turbulentflow along the mold (1) and generate a flow field which gives a higherheat transfer rate in total.

When using the mold for the production of confectionery products, aconfectionery material is introduced into at least one cavity of themold. Subsequently, the confectionary material is processed in at leastone cycle of supplying one of a cooling fluid and a heating fluid to themold such that the fluid flows along the bottom surface of the mold.During the cycle(s), the fluid flows along at least one protrudingelement so as to increase the heat transfer rate between the mold andthe fluid.

The protruding elements (5) may each be independently attached to thebottom surface of the mold (1) according to the present invention and donot necessarily form parts of the cavities (2 a).

In a further embodiment, at least some protruding elements (5) may bearranged to provide angularly offset portions relative to a directionparallel to the fluid flow between the side faces of the mold. Inparticular, the offset portions may be oriented according to either oneof two offset angles relative to a direction parallel to the fluid flow.

In an alternative embodiment, at least some protruding elements (5) maybe arranged in alternatively diverging and converging opposing pairsextending from one side face having openings (4) to the other side facehaving openings (4), the alternating divergence and convergence beingalong a direction parallel to the fluid flow. Molds (1) which havevortex generating elements (5) according to the embodiment describedabove are illustrated in FIGS. 3, 6, and 7.

In another embodiment, at least some protruding elements (5) arearranged in blocks, extending from one side face having openings (4) tothe other side face having openings (4), and are separated bystrengthening ribs (6), in a direction parallel to the fluid flow. Amold (1) according to the embodiment described above is shown in FIG. 4.The fluid flow and generated heat flux as result of the vorticesgenerated by the protruding (vortex generating) elements (5) is furthershown in FIG. 5.

The use of blocks of protruding elements (5) facilitates greater controlover the heat transfer distribution between the mold (1) and fluid.

In an alternative embodiment, at least some protruding elements (5) arearranged in blocks and further arranged to provide angularly offsetportions relative to a direction parallel to the fluid flow between theside faces of the mold. The offset portions may be oriented according toeither one of two offset angles relative to a direction parallel to thefluid flow.

Where the protruding elements (5) are arranged in blocks and in eitherone of two offset angles as described above, any one block may containelements arranged in only one of the two orientations or, alternatively,any one block may contain elements arranged in both orientations. In theformer configuration, adjacent blocks may contain elements configured inalternating orientations, e.g. with a given block in one orientationbeing positioned in between two blocks with the alternative orientation.

As already described above, the fluid is not particularly limited; saidfluid can be, for instance, cooling air or heating air. Alternatively,the fluid can be water or another medium for cooling/heating themold/product system during the manufacturing process.

The material of mold (1) is not particularly limited; the material can,for instance, be a polycarbonate (e.g. Makrolon, Lexan or Tarflon),preferably a material with higher heat conductivity and preferably amaterial with higher rigidity against physical tension or both.

In a further embodiment, the mold (1) according to present inventionfurther comprises at least one temperature sensor and/or at least onelogger for controlling of the temperature distribution during themanufacturing process. FIG. 8 illustrates a mold employing temperaturesensors and a logger for the measurement of online processing parametersand line performances.

The use of a mold (1) according to any one of the preceding embodimentsfor the production of confectionery products is advantageous in that ithas optimized heat transfer properties, thereby generally reducing theoverall energy consumption of the manufacturing process.

The confectionery product is sugar (or sugar-substitute) and fat based.Examples include chocolate, caramel, toffee and confectionery emulsions.Preferably, the confectionery product is chocolate, i.e. theconfectionery mass comprises, or consists of, tempered chocolate,meaning that the chocolate has undergone controlled heating and cooling.

The shape of the confectionery product produced with the mold (1)according to the present invention is not particularly limited; theconfectionery product can, for instance, be a block or tablet (with orwithout breakable portions), a thin sheet or slice, an individualportion or a bar.

The process for the production of confectionery products, wherein theconfectionery product is contained in the mold (1) according to thepresent invention is advantageous, since the energy optimized mold (1)ensures a more homogenous solidifying during the manufacturing processand further reduces the energy consumption of the production line.

The invention claimed is:
 1. A mold for the production of confectioneryproducts, comprising a top surface having cavities and an oppositebottom surface, comprising a plurality of protruding elements at thebottom surface of the mold, and opposite at least one of the cavities,for increasing the heat transfer rate between the mold and a fluidflowing along the bottom surface, wherein at least some of theprotruding elements are at non-parallel angles relative to others of theprotruding elements; wherein at least some protruding elements arearranged in blocks, extending from one side face having openings to theother side face having openings, and separated by strengthening ribs, ina direction parallel to the fluid flow.
 2. The mold according to claim1, further comprising at least one side face in which at least oneopening is provided for supplying a fluid to the bottom surface, atleast one opening preferably being provided in each of two opposing sidefaces of the mold.
 3. The mold according to claim 1, further comprisingat least one opening in the top surface of the mold.
 4. The moldaccording to claim 1, wherein the protruding elements are configured togenerate vortices in the fluid flowing along the bottom surface andpreferably to change the fluid flow characteristics along the mold byeffecting a more turbulent flow of the fluid.
 5. The mold according toclaim 1, wherein one or more of the protruding elements are arranged toprovide angularly offset portions relative to a direction parallel tothe fluid flow between the side faces.
 6. The mold according to claim 5,wherein the offset portions are oriented according to either one of thetwo offset angles relative to a direction parallel to the fluid flow. 7.The mold according to claim 5, wherein at least some protruding elementsare arranged in alternating diverging and converging opposing pairsextending from one side face having openings to the other side facehaving openings, the alternating divergence and convergence being alonga direction parallel to the fluid flow.
 8. The mold according to claim1, wherein at least some protruding elements are arranged in blocks andthe offset portions are oriented according to either one of two offsetangles relative to a direction parallel to the fluid flow.
 9. The moldaccording to claim 1, wherein one or more protruding elements areconfigured to guide the fluid flow along the bottom surface of saidmold.
 10. The mold according to claim 1, wherein the fluid is coolingair or heating air.
 11. The mold according to claim 1, wherein the moldis at least partially made of polycarbonate.
 12. The mold according toclaim 1, further comprising at least one temperature sensor and alogger.